In gas meters, and in particular so-called "domestic" gas meters, it is known to install a gas flow interrupter upstream from the measurement chamber of said meter for safety purposes. For example, in the event of a gas leak, gas meters detect a leakage flow rate, thereby automatically causing the interrupter to interrupt the gas flow.
Such an interrupter is also used when the gas meter is fitted with a prepayment system, in which case it serves to interrupt the flow of gas when the user's credit is exhausted.
For example, a known gas meter interrupter comprises a valve member that is movable relative to a valve seat and in which the valve member is constituted by a resilient membrane that is hemispherical in shape and is hinged about a pivot that forms a ball joint connection. When a fire breaks out, provision is made for the interrupter to be activated to take up its closed position and interrupt the flow of gas.
Unfortunately, with an interrupter as described above, the resilient membrane melts at high temperature and as a result the valve member can no longer perform the sealing function required of the interrupter in the closed position, which constitutes a major drawback.
Another type of interrupter is known in which the valve member is mainly formed by a central part hinged about a pivot, a substantially plane spring fixed around said central part, and a resilient membrane covering the central part and the spring, and overlying the peripheral portion of said spring.
At high temperature, the interrupter actuated into its closed position closes the valve seat and the membrane melts so that the central part and the spring of the valve member become exposed to the flow of gas and can no longer perform the sealing function.
Sometimes, the membrane of a valve member in an interrupter is not always gastight for various reasons, e.g. associated with the material of the membrane or with the method by which it is made. For these reasons, it can be advantageous to design a valve member that is capable of diminishing leakage associated with the membrane, regardless of temperature.